This invention relates in general to internal combustion engines powered by volatile liquid fuels and, more particularly, to carburetors for such engines.
The typical automotive engine is powered by gasoline which is mixed with air at a carburetor to produce a combustible mixture that burns within the engine to produce useful energy. Ideally, the gasoline should be a vapor, for the mixture will then burn uniformly and more completely within the cylinder. This in turn provides greater efficiency and produces less pollutants. Conventional carburetors, however, tend to atomize much of the gasoline instead of vaporizing it. As a consequence, the mixture is overly rich in gasoline, and when burned produces an excessive amount of pollutants. Furthermore, because the mixture is so rich, the engine operates inefficiently and this translates into relatively low gas mileage in the case of automobiles.
One type of carburetor that is used quite extensively on V-8 automobile engines of recent manufacture has two barrels, and at the entrance to each barrel it is provided with a booster venturi tube which is nothing more than a short tube having orifices opening out of it. These orifices in turn are connected by passageways to the carburetor float bowl. The tubes reduce the cross sectional areas through which the air flows and thereby create a venturi effect. As a consequence, gasoline is drawn out of the orifices and into the airstream where it mixes with the air to form a combustible mixture. Even so, much of the gasoline is merely atomized, and the mixture is normally excessively rich in gasoline. In some of the carburetors the venturi tubes are die cast into a cluster or single unit, and that unit in turn is bolted to the main body of the carburetor. Hence it can be removed quite easily.
Another type of carburetor, which is found primarily on six cylinder engines of recent manufacture has a single barrel that narrows down to a venturi into which a fuel discharge tube opens. This tube is connected with the float bowl of the carburetor so that fuel flows from the tube into the region of reduced pressure in the venturi. Again much of the gasoline merely remains atomized in the barrel, and the mixture that is formed is overly rich in gasoline.